In many installations it is common to have more or less permanent piping with nozzles ejecting water or water mist. Examples of such installations include buildings, ships, offshore installations, tunnels, mines, or generally any facility or location at which it is desired to be able to put out or prevent fire. Sprinkler systems have been used in such installations for a long time.
In many situations, the use of water mist is preferable to sprinkler systems from which water is discharged in the form of larger drops, because water mist often provides for a more efficient fire-extinguishing, requires less water, causes less water damages, may be used in connection with fire in liquids and gases, and has a lesser negative impact on electric installations. Water mist systems may be used anywhere as a replacement for sprinkler systems. In connection with permanently installed fire extinguishing systems it is common for the fire-extinguishing assemblies to be under a certain water pressure. These characteristics are common for prior art sprinkler systems and fire extinguishing assemblies. Heat-sensitive glass bulbs are commonly used in permanently installed fire extinguishing systems.
However, water-based fire extinguishing assemblies suffer from certain associated disadvantages. Such assemblies are often manufactured with small nozzle openings which easily become clogged by contaminations in the water, and therefore normally a screening or water filtering system is required. Also, such assemblies typically have been relatively weighty, which is undesirable especially on vessels and floating structures as a large number of assemblies are required which combines to increase the overall weight significantly. Moreover, many of these assemblies also require a high inlet pressure in order to function properly, which increases the complexity, the necessary rating of the piping, the costs, as well as reduces the reliability particularly in case of fire. In addition, another problem is related to seals of known assemblies, and poor seals may result in leaks disrupting the mist pattern. Many assemblies also produce a relatively poor spreading of the mist, and a single generator, therefore, may only be used in rooms of a relatively limited size.
From NO 314835 an arrangement is disclosed for providing small water droplets, for use in particular for water-based fire-extinguishment. The arrangement is adapted for pivoting around its own axis, and is constituted by a hollow shaft. At least two circular water distribution disks are attached to the one end of the shaft by way of bolts. The water distribution disks are arranged in a spaced relation by means of spacers on the bolts. Each water distribution disk has an open center section, an inner horizontal annular surface, a steeply descending section, a less steeply descending section, as well as a narrow outer horizontal surface. A water supply conduit is provided in the hollow shaft. The conduit connects to a water supply at a one end and is closed and protrudes to the lowermost water distribution disk at the other end. The conduit comprises at least a water outlet at the levels in between two by two water distribution disks.